Package delivery companies pick up millions of packages daily from thousands of locations over a large geographical area and transport them, primarily by truck and airplane, to a correspondingly large number of scattered destinations. To meet a rigorous schedule and provide accurate deliveries, a package delivery company must use automated transfer systems to match incoming packages with proper outgoing transport headed for the packages' destinations. Because deliveries are time sensitive, the sorting equipment must be very fast, yet provide gentle and accurate handling of packages.
Belt and roller conveyor systems have often been used in package sorting systems to move packages from incoming loading docks to outgoing transport. A initial sorting of packages traveling along a conveyor may be accomplished by diverting packages from the conveyor based on their destinations, or based on their size or another characteristic.
To automate handling of articles in conveyor systems, conveyor diverter assemblies of various types have been developed. Roller bed diverters using right angle transfer belts are shown in U.S. Pat Nos. 4,798,275 to Leemkuil et. al., and 4,174,774 to Bourgeois. However, these diverter systems divert articles at right angles to the primary conveyor direction of travel. Therefore, the article must be slowed so that it may be frictionally engaged by transfer belts for the radical right angle change of direction. If the article is traveling at high speed, it may slide through the diverter, out of control, before it can be diverted. Thus, production speed must be sacrificed for accuracy in the sorting process.
Other diverter systems have been developed to divert the articles from the main conveyor diagonally. U.S. Pat. No. 3,219,166, discloses a main conveyor consisting of cone-shaped, powered rollers, positioned so that the large diameter end alternates one on the left side, next on the right. All the rollers with the large end on the left are linked and can be lowered together, and the same is true for the rollers with the large end on the right. When both left and right sets are elevated, the net force on the parcels is straight. When one set is lowered, the other set acts on the parcel and diverts it off the main conveyor at an angle. Although both the left and right set of rollers can act on the parcels simultaneously, each set on its own has only a small tendency to turn and slide the parcels toward the side, resulting from the taper of the rollers. There is no direct force driving the parcels in the direction of one of the discharge conveyors positioned along the main conveyor.
U.S. Pat. No. 5,551,543 shows a sorter with angled rollers to divert parcels at an angle. In one embodiment, the parcels are either carried straight through on chains, or lowered onto diverting idler rollers while being pushed. In another version, steerable idler rollers guide the parcel either straight or off to the side. In another version, the angled idler rollers are shifted up into contact with the parcels. In a final version, there are two sets of idler wheels arranged at different angles, one of which is vertically movable. At any particular output location along the main conveyor path, the products can only be diverted to one side of the path.
U.S. Pat. No. 3,608,713, has a main conveyor consisting of angled, powered rollers mounted to travel with a chain drive. If a parcel is to move straight with the conveyor, the rollers do not rotate. If the parcel is to be diverted, the powered rollers are activated to divert the parcel without slowing the chain drive. The apparatus only diverts in the direction the rollers are angled, and requires a complex mechanism to carry all the rollers with the chain conveyor.
U.S. Pat. No. 3,926,298, provides a main conveyor having multiple powered wheels, and a diagonal belt conveyor fitted between the wheels below the normal conveyor surface. A section of the drive rollers can be lowered to drop a parcel onto the belt conveyor, without interrupting the speed of articles moving along the primary path. However, the belt conveyor can divert in only one direction.
Thus, there is a need in the art for a diverter that can directly and forcefully drive a parcel diagonally to either side of a main conveyor path, or pass the parcel straight through the diverter location, all while operating at a high speed of throughput along the main path.